Brachial Plexus Injuries

Question 1

What can cause damage to the brachial plexus?

Answer 1

• Injuries at birth (obstetric) - Blunt trauma - Penetrating trauma – wounds to the neck or axilla - Disease

Question 2

What are injuries to the superior parts of the BP called? What nerve roots are injured?

Answer 2

Upper BP injury known as ‘Erb’s palsy’ C5 and C6 (sometimes C7 but not always)

Question 3

What are injuries to the inferior parts of the BP called?

Answer 3

Lower BP injury known as ‘Klumpke’s palsy’

Question 4

What happens if the whole plexus is injured?

Answer 4

Rarely, the whole plexus can be injured – these injuries are devastating.

Question 5

What part of the BP can cervical cord injuries injure?

Answer 5

The roots of the BP

Question 6

What part of the BP can 1st rib injuries injure?

Answer 6

The trunks of the BP

Question 7

How does obstetric upper BP injury occur?

Answer 7

Occurs due to excessive stretching of the baby’s neck during delivery causing damage to C5 and C6 nerve roots

Question 8

When does excessive stretching of the baby’s neck during delivery typically occur?

Answer 8

Usually when the baby’s shoulders are ‘stuck’ (shoulder dystocia)

Question 9

What does upper BP injury lead to?

Answer 9

Paralysis of upper limb muscles that are supplied by C5 and C6 (and possibly C7)

Question 10

What muscles are affected in upper BP injury?

Answer 10

Musculocutaneous nerve (C5-C7):

• Coracobrachialis
• Biceps
• Brachialis

Axillary nerve (C5 and C6):

• Deltoid
• Teres minor

Suprascapular nerve also arises from the upper trunk of the brachial plexus derived from roots C5 and C6 which innervates infraspinatus and supraspinatus

Question 11

Why are motorbike accidents (or similar to this) a common cause of brachial plexus injuries?

Answer 11

Causes stretching of neck from shoulder due to accident –> damages brachial plexus

Question 12

Here is a photograph of a baby with Erb’s palsy. Explain why the arm is positioned this way due to damage to nerves.

Answer 12

• Biceps and brachialis (C5, C6, C7)
  
  • Loss of elbow flexion by both
  • Loss of supination of forearm by biceps
• Teres minor and infraspinatus (C5, C6)
  
  • Unopposed medial rotation of the shoulder as lateral rotators arren’t working
• Deltoid (axillary nerve C5, C6)
  
  • Arm is limp by side due to loss of abductors
• Sensory deficits in C5/C6 (C7) dermatomes

Question 13

What investigations are done in adult upper limb injury?

Answer 13

MRI: shows nerve root damage.

Question 14

Where does the suprascapular nerve arise?

Answer 14

Arises from the superior trunk of the brachial plexus

Question 15

Is obstetric lower BP injury or upper BP injury more common?

Answer 15

Erb’s palsy (upper BP injury) more common during delivery

Question 16

What does lower BP injury lead to?

Answer 16

Paralysis of the UL muscles that are supplied by C8 and T1, and possibly C7.

Question 17

Later in life, what can obstetric brachial plexus injuries lead to?

Answer 17

Poor development of muscles supplied by nerves that are injured

Question 18

What causes obstetric lower BP injuries?

Answer 18

Excessive pulling on the baby’s upper limb during delivery causing damage to C8 and T1 nerve roots

Question 19

What are adult lower BP injuries typically caused by?

Answer 19

Occur when excessive force is placed on an abducted shoulder and usual mechanism is that the upper limb is suddenly pulled superiorly e.g. grasping to prevent a fall

Question 20

The function of which nerve will be impaired by a C8 and T1 root injury?

Answer 20

Ulnar nerve

Question 21

What muscles does the ulnar nerve innervate in the:

• Arm?
• Forearm?
• Hand?

Answer 21

Arm –> none

Forearm:

• Flexor carpi ulnaris
• 1/2 digitorum profundus

Hand:

• Intrinsic muscles of the hand: hypothenar, adductor pollicis, palmaris brevis, palmar and dorsal interossei of the hand, medial two lumbricals

Question 22

Which areas of skin are innervated by C8 and T1?

Answer 22

Medial side of hand and forearm

Question 23

How can a lower BP injury affect the hand?

Answer 23

Can lead to paralysis of the majority of the intrinsic hand muscles

Question 24

What is ‘claw hand’?

Answer 24

• After a lower BP injury
• An ‘imbalance’ between the ongoing function in some intrinsic & extrinsic muscles but paralysis / weakness in others leads to hand deformity

Question 25

What other syndrome can a lower BP injury be associated with?

Answer 25

Horner’s syndrome

Question 26

What are the features of Horner’s syndrome?

Answer 26

• Ptosis
• Miosis
• Anhidrosis
• Vasodilation

Question 27

What is ptosis of the eye?

Answer 27

Drooping of the upper eyelid

Question 28

What is miosis of the eye?

Answer 28

Excessive constriction of the pupil of the eye.

Question 29

What is anhidrosis?

Answer 29

Absence of sweating

Question 30

Why might a person with Klumpke’s paralysis also have Horner’s syndrome?

Answer 30

Sympathetic neurons supplying the head originate from T1 and may also be damaged by traction.

These neurons cause the pupil to dilate.

Question 31

What is Horner’s syndrome?

Answer 31

Horner syndrome is a combination of signs and symptoms caused by the disruption of a nerve pathway from the brain to the face and eye on one side of the body

Question 32

What are the 3 key features of Horner’s syndrome?

Answer 32

1. decreased pupil size
2. a drooping eyelid
3. decreased sweating on the affected side of your face.

Question 33

Where do sympathetic nerves supplying the head originate?

Answer 33

Thoracic region (T1-T6)

Question 34

Effect of sympathetic nervous system on pupil constriction?

Answer 34

Causes pupil dilation